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TCAN1043HG-Q1: how would we turn Inhibit off

Viktorija Cecil
Mastermind 18061 points
Part Number: TCAN1043HG-Q1

Team,

The datasheet mentions that the WAKE “terminal triggers a LWU on either a low-to-high or high-to-low transition since it uses a bi-directional input threshold (falling or rising edge)”. In the case we consider a low-to-high configuration and use vehicle ignition as the WAKE source, how would we turn Inhibit off? The only way I see to do this is to drive nSTB low via the MCU.

Thanks

Viktorija

  • 0
    TI__Intellectual 2090 points

    Hi Viktorija,

    The INH pin is designed to be high for all modes, with the exception of Sleep Mode when the INH pin will output high-Z and decay to 0V.  In normal device operation (outside of an under voltage or thermal event), the only way to enter Sleep Mode is through an MCU command to set nSTB low and EN high, as you have stated above.  When a wake request is received in Sleep Mode (LWU via WAKE pin in your case) then the device will transition to Standby Mode, and the INH pin will rise.

    Do you intend to use the INH pin functionality for a system level enable pin in your application?  For what reason do you desire the INH pin to be turned off?

    Thanks,
    Max Megee

    INT-TRX Applications

  • 0 in reply to Max Megee
    Prodigy 100 points

    Hi Max,

    I appreciate the insight you provided.

    Yes, ideally I would like to use this as a system level enable in my application. In this case, I would like INH to go low in a key-off event (i.e. when WAKE goes low).

    Thank you,

    -Kade

  • 0 in reply to Kade Hudson
    TI__Intellectual 2090 points
    Gotcha.
    One thing you may want to keep in mind: the only intended function of the WAKE pin is to bring the device out of Sleep Mode. The WAKE pin has no influence on the INH pin or on the device to transition to Sleep Mode.
    If the INH pin controls the system enable for the voltage regulators, then you should be able to issue a Sleep Mode transition command from the MCU after the key-off event. Then INH will drop and the regulators will disable the node at the system level.

    Does this make sense in your application?

    Max
  • 0 in reply to Max Megee
    Prodigy 100 points

    It might. I'll have to review with the team.

    I do however, have another question. I'm not sure I am understanding the undervoltage condition. According to the datasheet, the only way to come out of the undervoltage mode is when Vcc or Vio are less than their undervoltage conditions. I think I am missing a fundamental concept here. Can you please explain how this works?

  • 0 in reply to Kade Hudson
    TI__Guru 62910 points
    Hi Kade,

    I understand the confusion. Under-voltage in this diagram is not intended to be defined as a mode in itself. Rather, we are trying to say that an under-voltage condition at any time would prompt a transition into sleep mode. Please let me know if that does not make sense.

    Regards,
    Max
  • 0 in reply to Max Robertson
    Prodigy 100 points

    Max,

    The diagram is confusing for me, but you're explanation clears it up. Thank you for the help!

    -Kade